Humidifier heater base

ABSTRACT

A humidifier heater base assembly has a heater plate with a thermally conductive portion and a perimeter portion around a perimeter of the heater plate. A resilient member has an inner part attached to the perimeter portion and an outer part adapted to provide a resilient perimeter flange around at least part and preferably the whole of the perimeter portion. The resilient member fixes the heater base to the humidifier by the resilient perimeter flange such that the heater plate and the inner part can move relative to the humidifier in a direction substantially transverse to the general plane of the heater plate. At least a portion of the resilient perimeter flange remains stationary relative to the humidifier.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/248,663, filed Jan. 15, 2019, which is a continuation of U.S. patentapplication Ser. No. 14/838,168, filed Aug. 27, 2015, now U.S. Pat. No.10,252,019, issued on Apr. 9, 2019, which is a continuation of U.S.patent application Ser. No. 13/375,975, filed Jan. 4, 2012, now U.S.Pat. No. 9,174,017, issued on Nov. 3, 2015, which is a national phase ofInternational Application No. PCT/NZ2010/000103, filed Jun. 3, 2010,which claims priority from U.S. Provisional No. 61/184,379, filed Jun.5, 2009.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a gas humidification apparatus, particularlybut not solely for humidifying a gases supply to a patient or user whorequire a supply of humidified gas for the treatment of diseases such asObstructive Sleep Apnea (OSA), snoring, or Chronic Obstructive PulmonaryDisease (COPD) and the like. In particular, this invention relates tothe heater base arrangement of a humidification apparatus.

Description of the Related Art

Devices or systems for providing a humidified gases flow to a patientfor therapeutic purposes are well known in the art. Systems forproviding therapy of this type, for example CPAP therapy, have astructure where gases at the required pressure are delivered from anassisted breathing unit or blower unit to a humidifier chamberdownstream from the blower. As the gases are passed through the heated,humidified air in the humidifier chamber, they become saturated withwater vapour. The gases are then delivered to a user or patientdownstream from the humidifier, via a gases conduit. Humidified gasescan be delivered from a modular system that has been assembled fromseparate units (that is, a system where the humidifier chamber/heaterand the breathing unit/blower are separate items) connected in seriesvia conduits. However, it is becoming more common for integratedblower/humidifier systems to be used, as shown schematically in FIG. 1.A typical integrated system consists of a main ‘blower’ or assistedbreathing unit which provides a pressurised gases flow, and a humidifierunit that mates with or is otherwise rigidly connected to the blowerunit. This mating occurs for example by a slide on or push connection,so that the humidifier is held firmly in place on the main blower unit.An example of a system of this type is the Fisher and Paykel Healthcare‘slide-on’ water chamber system shown and described in U.S. Pat. No.7,111,624.

Integrated devices are generally more compact and discrete than modularbreathing circuit that have been assembled from separate units. Acompact and discrete unit is particularly advantageous for home useunits, where bedside space is limited, and where a user may also have totransport and set up their own personal unit elsewhere, for example ifstaying overnight away from home. With compact and integrated units, theset up is generally easier for a user.

Generally, home units are used for the relief of sleep apnoea. A mid-usepoint will usually be during the night, during a users sleep cycle. Ifrefilling or similar is required during use, a user will need to wake upto perform this operation. Having been woken up, the user is required torefill the humidifier chamber. Problems can arise when filling orcleaning these units, as nearly all of the respiratory humidificationsystems currently available use water as a humidification medium, andcleaning will almost always be carried out with a water based cleaner.Blower and humidifier units are operated and controlled electrically,and problems can occur if the internal electronic parts are notprotected. If the internal parts are not protected, any accidental waterspillage that takes place can potentially short-circuit the electronicsand disrupt the operation of the system.

It is an object of the present invention to provide a breathingassistance apparatus which goes some way to overcoming theabovementioned disadvantages or which at least provides the public orindustry with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, the present invention broadly consists in a heaterbase assembly for use in a humidifier of the type which is used forheating and humidifying a flow of respiratory gases supplied to a user,comprising: a heater plate having a thermally conductive portion and aperimeter portion around the perimeter of said heater plate, a resilientmember having a first portion coupled to said heater plate and a secondportion adapted to provide a flange around at least part of saidperimeter portion, said resilient member adapted to allow said heaterbase to be fixed to said humidifier by said flange in such a manner thatsaid heater plate and said first portion can move relative to saidhumidifier.

In a second aspect the present invention broadly consists in a heaterbase assembly for use in a humidifier of the type which is used forheating and humidifying a flow of respiratory gases supplied to a user,comprising: a heater plate and a resilient member fixed to the heaterplate for resiliently mounting the heater plate to the humidifier andproviding a fluid barrier between the heater plate and the humidifier.

Preferably the resilient member is a flexible gasket or diaphragm forresiliently fixing the heater plate to said humidifier.

Preferably said resilient member is moulded to said heater plate.

Preferably the first portion is attached to the perimeter portion of theheater plate.

Preferably the flange extends around the full perimeter of the heaterplate.

Preferably the resilient member is adapted to allow said heater base tobe fixed to said humidifier by said flange in such a manner that saidheater plate and said first portion can move relative to said humidifierin a direction substantially transverse to the general plane of saidheater plate.

Preferably said thermally conductive portion of said heater plate issubstantially planar, and at least part of said perimeter portion isformed out of plane from said thermally conductive portion.

Preferably said thermally conductive portion of said heater plate has anupper surface adapted for supporting a humidifier chamber in use, andsaid perimeter portion is formed so that in use at least part of saidperimeter portion is below said upper surface.

Preferably the flange is adapted to be clamped between two humidifiercomponents to secure the heater base to the humidifier, at least aportion of the flange being adapted to be at least slightly compressedbetween the two humidifier components.

Preferably the flange is adapted to be clamped between an upperhumidifier component and a lower humidifier component, at least aportion of the flange being adapted to be at least slightly compressedbetween the upper humidifier component and the lower humidifiercomponent.

Preferably said resilient member has an upper circumferential grooveformed in the upper surface of said flange for accepting a correspondingcircumferential projection extending downwards from an upper humidifiercomponent.

Preferably said resilient member has a lower circumferential grooveformed in the lower surface of said flange for accepting a correspondingcircumferential projection extending upwards from a lower humidifiercomponent.

Preferably said upper and lower circumferential grooves are verticallyaligned.

Preferably a portion of the flange is adapted to in use provide a fluidbarrier between the heater base and a humidifier component.

Preferably a portion of the flange is adapted to in use provide a fluidbarrier between the heater base and a humidifier component, the fluidbarrier being located between the upper groove and a lower humidifiercomponent.

Preferably a portion of the flange is adapted to in use provide a fluidbarrier between the heater base and a humidifier component, the fluidbarrier being located between the lower groove and an upper humidifiercomponent.

Preferably in use a portion of said flange is elastically compressed bysubstantially between 4% and 20%.

Preferably in use a portion of said flange is elastically compressed bysubstantially 12%.

Preferably at least one and preferably both of said upper and lowercircumferential grooves taper from a wide mouth to a narrow base.

Preferably said resilient member comprises a narrow section formed insaid resilient member between said first portion and said flange, saidnarrow section providing an area in which said resilient memberpreferentially elastically deflects when said heater plate is displacedrelative to said flange of said resilient member in a directionsubstantially transverse to said general plane of said heater plate inuse.

Preferably said narrow section comprises a circumferential valley formedin either an upper surface or a lower surface of said resilient memberor both.

Preferably said resilient member comprises a skirt section formed insaid resilient member between said first portion and said flange, in usesaid skirt section elastically deflecting when said heater plate isdisplaced relative to said flange of said resilient member in adirection substantially transverse to said general plane of said heaterplate.

Preferably the first portion is vertically spaced from the flange by theskirt section.

Preferably said resilient member is formed as a continuous layer acrossthe upper surface of said heater plate, said continuous layer completelycovering said upper surface.

Preferably said heater base further has a heating element attached tothe underside of said heater plate.

Preferably said heater base further has at least one electricalcomponent coupled to the underside of said heater plate, and saidresilient member further has a channel formed in the lower surface ofsaid resilient member and running from an inner part or surface of saidresilient member to an outer part or surface of said resilient member,said electrical component further having electrical wires that in useextend from said electrical component across said resilient member viasaid channel.

Preferably in use the resilient member forms a fluid barrier between theheater plate and the humidifier.

In a third aspect the present invention broadly consists in a humidifierof the type which is used for heating and humidifying a flow ofrespiratory gases supplied to a user, said humidifier adapted to heatthe contents of a humidifier chamber which is removably attached in useto said humidifier, said humidifier comprising: a casing or base unit,adapted to hold said humidifier chamber in position relative to saidhumidifier, a heater base fixed to said casing or base unit, comprisinga heater plate and a resilient member, a heating element, said heaterplate having a thermally conductive portion and a perimeter portionaround the outside of said thermally conductive portion, said resilientmember having a first portion coupled to the heater plate, and secondportion providing a flange around at least part of said perimeterportion, said heater base fixed to said casing or base unit by saidflange in such a manner that said heater plate and said first portioncan move relative to said casing or base unit, said heating elementadapted to provide heat to said thermally conductive portion of saidheater plate in use.

In a forth aspect the present invention broadly consists in a humidifierof the type which is used for heating and humidifying a flow ofrespiratory gases supplied to a user, said humidifier adapted to heatthe contents of a humidifier chamber which is removably attached in useto said humidifier, said humidifier comprising: a casing or base unit,adapted to hold said humidifier chamber in position relative to saidhumidifier, a heater base fixed to said casing or base unit, comprisinga heater plate and a resilient member fixed to the heater plate forresiliently mounting the heater plate to the casing or base unit andproviding a fluid barrier between the heater plate and the casing orbase unit, and a heating element for providing heat to the heater plate.

Preferably the resilient member is a flexible gasket or diaphragm forresiliently fixing the heater plate to the humidifier.

Preferably said resilient member is moulded to said heater plate.

Preferably the first portion is attached to the perimeter portion of theheater plate.

Preferably the flange extends around the full perimeter of the heaterplate.

Preferably the resilient member is fixed to said casing or base unit bysaid flange in such a manner that said heater plate and said firstportion can move relative to said humidifier in a directionsubstantially transverse to the general plane of said heater plate.

Preferably said thermally conductive portion of said heater plate issubstantially planar, and said perimeter portion is formed out of planefrom said thermally conductive portion.

Preferably said thermally conductive portion of said heater plate has anupper surface adapted for supporting a humidifier chamber in use, andsaid perimeter portion is formed so that in use at least a part of saidperimeter portion is below said upper surface.

Preferably the casing or base unit further comprises two humidifiercomponents and the flange is clamped between said two humidifiercomponents to secure the heater base to said casing or base unit, atleast a portion of the flange being at least slightly compressed betweenthe two humidifier components.

Preferably the casing or base unit further comprises an upper humidifiercomponent and a lower humidifier component and the flange is clampedbetween said upper humidifier component and said lower humidifiercomponent, at least a portion of the flange being at least slightlycompressed between the upper humidifier component and the lowerhumidifier component.

Preferably said resilient member has an upper circumferential grooveformed in the upper surface of said flange, and said upper humidifiercomponent has a corresponding circumferential projection extendingdownwards from said upper humidifier component and into said uppercircumferential groove.

Preferably said resilient member has a lower circumferential grooveformed in the lower surface of said flange, and said lower humidifiercomponent has a corresponding circumferential projection extendingupwards from said lower humidifier component and into said lowercircumferential groove.

Preferably said upper and lower circumferential grooves andcorresponding said projections are vertically aligned.

Preferably a portion of the flange provides a fluid barrier between theheater base and a said humidifier component.

Preferably a portion of the flange provides a fluid barrier between theheater base and the humidifier casing or base unit and the fluid barrieris located between the upper groove and the humidifier lower component.

Preferably a portion of the flange provides a fluid barrier between theheater base and the humidifier casing or base unit and the fluid barrieris located between the lower groove and the humidifier upper component.

Preferably in use a portion of said flange is elastically compressed bysubstantially between 4% and 20%.

Preferably in use a portion of said flange is elastically compressed bysubstantially 12%.

Preferably at least one and preferably both of said upper and lowercircumferential grooves taper from a wide mouth to a narrow base, thecorresponding projections being correspondingly tapered to match.

Preferably said resilient member comprises a narrow section formed insaid resilient member between said first portion and said flange, saidnarrow section providing an area in which said resilient memberpreferentially elastically deflects when said heater plate is displacedrelative to said flange of said resilient member in a directionsubstantially transverse to said general plane of said heater plate inuse.

Preferably said narrow section comprises a circumferential valley formedin either an upper surface or a lower surface of said resilient memberor both.

Preferably said resilient member comprises a skirt section formed insaid resilient member between said first portion and said flange, in usesaid skirt section elastically deflecting when said heater plate isdisplaced relative to said flange of said resilient member in adirection substantially transverse to said general plane of said heaterplate.

Preferably the first portion is vertically spaced from the flange by theskirt section.

Preferably said resilient member is formed as a continuous layer acrossthe upper surface of said heater plate, said continuous layer completelycovering said upper surface.

Preferably said heater base further has a heating element attached tothe underside of said heater plate.

Preferably said heater base further has at least one electricalcomponent coupled to the underside of said heater plate, and saidresilient member further has a channel formed in the lower surface ofsaid resilient member and running from an inner part or surface of saidresilient member to an outer part or surface of said resilient member,said electrical component further having electrical wires that in useextend from said electrical component across said resilient member viasaid channel.

Preferably in use the resilient member forms a fluid barrier between theheater plate and the humidifier.

Preferably said upper component is the wall of a humidifier chambercompartment adapted for containing a humidifier chamber in use.

Preferably a lower portion of said wall of said humidifier chambercompartment includes a horizontal wall section, said flange beingclamped between said horizontal wall section and said humidifier lowercomponent.

Preferably said heater base forms at least part of a base of saidhumidifier chamber compartment.

Preferably said horizontal wall section and said heater base form a baseof said humidifier chamber compartment.

Preferably an upper surface of the flange is off set downwardly relativeto the upper surface of the first portion of the resilient memberattached to the plate, so that an upper surface of the compartment wallhorizontal section is approximately in plane with said upper surface ofthe first portion.

Preferably said humidifier comprises a locking mechanism for retainingsaid humidifier chamber in an installed position with the base of saidhumidifier chamber adjacent to and contacting said heater plate, andwhen in said installed position said base of said humidifier chamberdisplaces said heater plate downwards, said resilient member biasingsaid heater plate upwards against said base of said humidifier chamber.

Preferably said locking mechanism is movable from an unlocked positionto a locked position and back again, in use movement from said unlockedto said locked position presses said humidifier chamber downwardsagainst said heater plate by a distance, thereby displacing the heaterplate downwards by said distance.

Preferably said heater base is assembled to said casing or base unit insuch a manner that there is a gap below a bottom surface of saidresilient member or heater plate or both, said gap sized to allow saidheater plate to displace downwardly from a neutral position in use, thegap being greater than said distance.

Preferably said heater element is attached to an underside of saidheater plate.

Preferably said heater element contacts an underside of the heater platewhen said heater plate is displaced downwards to at least said installedposition, said heater element out of contact with said heater plate whensaid heater plate is in a raised uninstalled position.

The term “comprising” as used in this specification and claims means“consisting at least in part of”. When interpreting each statement inthis specification and claims that includes the term “comprising”,features other than that or those prefaced by the term may also bepresent. Related terms such as “comprise” and “comprises” are to beinterpreted in the same manner.

To those skilled in the art to which the invention relates, many changesin construction and widely differing embodiments and applications of theinvention will suggest themselves without departing from the scope ofthe invention as defined in the appended claims. The disclosures and thedescriptions herein are purely illustrative and are not intended to bein any sense limiting.

The invention consists in the foregoing and also envisages constructionsof which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described by way ofexample only and with reference to the following drawings.

FIG. 1 shows a schematic view of a user receiving humidified air from anintegrated blower/humidifier system of a known, prior art, type.

FIG. 2 shows a perspective view of the preferred embodiment of theintegrated blower/humidifier (integrated unit) of one aspect of thepresent invention, the integrated unit having a separate humidifierchamber and blower unit which are both shown, with the humidifierchamber in place within the blower unit ready for use.

FIG. 3 shows a perspective view of the blower unit of FIG. 2, with thehumidifier chamber removed (not shown).

FIG. 4a shows a rear view of the blower unit of FIG. 2, with a sectionline D-D shown.

FIG. 4b shows a cross-sectional view along section line D-D of theblower unit of FIG. 2.

FIG. 5 shows an exploded view of the blower unit and the humidifierchamber of FIG. 2.

FIG. 6 shows a schematic detail view along section line DD of theinternal structure of the blower unit.

FIG. 7a shows a rear view of the humidifier chamber of the presentinvention, with a humidifier chamber lid and a locking handle shown inexploded view above the humidifier chamber, and a section line A-Ashown.

FIG. 7b shows a cross sectional view along the line A-A of thehumidifier chamber, humidifier chamber lid and locking handle of FIG. 7a.

FIG. 8 shows a cross section of a prior art heater plate mountingarrangement

FIG. 9a shows a cross-sectional view of a preferred form of a heaterbase assembly.

FIG. 9b shows a close-up of one side of the heater base assembly shownin FIG. 9 a.

FIG. 10a shows a cross section of an integrated unit that incorporatesthe heater base assembly of FIG. 9 a.

FIG. 10b shows a close up of the lower corner of the integrated unit ofFIG. 10a , showing structural detail of the wall and the base of theintegrated unit, and the relationship of the heater base assembly tothese items.

FIG. 11 shows a cross-sectional part view of an integrated unit with analternative form of a heater base assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A schematic view of the user 3 receiving air from a known, prior artintegrated blower/humidifier unit 5 is shown in FIG. 1. Pressurised airis provided from an assisted breathing unit or blower 1 to a humidifierchamber 2. Humidified, heated and pressurised gases exit the humidifierchamber 2 via a conduit 21, and are provided to the patient or user 3via a user interface 4. The user interface 4 shown in FIG. 1 is a nasalmask, covering the nose of the user 3. However, it should be noted thatin systems of these types, a full face mask, nasal cannula, tracheostomyfitting, or any other suitable user interface could be substituted forthe nasal mask shown.

The integrated blower/humidifier unit 6 of the present invention can besubstituted for the unit 5 of FIG. 1. A preferred form of the integratedblower/humidifier unit 6 is shown assembled and ready for use in FIG. 2.The integrated blower/humidifier unit 6 has two main parts: A blowerunit 7, having an outer shell 36 which forms part of the blower unit 7and also encloses the working parts of the blower unit—e.g. the fan,internal ducting and the internal control system; and a humidificationunit 31 (described in detail below).

Assisted Breathing Unit

The preferred form of assisted breathing unit or integratedblower/humidifier unit 6 will now be described with reference to FIGS.3-6.

The integrated blower/humidifier unit 6 consists of two main parts: anassisted breathing or blower unit 7 and a humidification unit 31. Thehumidification unit 31 is enclosed within the external casing of theintegrated blower/humidifier unit 6 in use, except for the top part. Thestructure of the humidification unit 31 is described in greater detailbelow. The blower unit 7 has an outer shell 36 which is a generallyrectangular block with substantially vertical side and rear walls, and afront face that is angled slightly rearwards. In the preferredembodiment, the walls, base and top surface are all manufactured andconnected as far as possible to minimise the occurrence of seams, andany necessary seams are sealed. This outer shell 36 encloses the workingparts of the blower unit 7, and forms part of the blower unit 7. Asshown in FIG. 3, a control knob 8 is located on the lower section of thefront face of the integrated blower/humidifier unit 6, with a controldisplay 9 located directly above the knob 8. A patient outlet 25 isshown passing out of the rear wall of the integrated blower/humidifierunit 6. In the preferred embodiment, in use the free end of the patientoutlet 25 faces upwards for ease of connection. However, the preferredform of patient outlet 25 can be rotated to one side or the other tomove or align it in a more convenient position for storage or for a moreconvenient use position. The patient outlet 25 is adapted to allow bothpneumatic and electrical connection to one end of a conduit—e.g. conduit21—running between the integrated blower/humidifier unit 6 and a patientinterface—e.g. interface 4.

In FIG. 2, a locking handle 22 is shown in position on the top surfaceof the integrated blower/humidifier unit 6. The locking handle 22 is aseparate item that can be unlocked and removed from the remainder of theintegrated blower/humidifier unit 6. The locking handle 22 includes agrip 30, adapted to act as a handle to allow a user to lift and carrythe integrated blower/humidifier unit 6, and also adapted to enable thelocking handle 22 to be rotated from a locked position to an unlockedposition. The locking handle 22 can be releasably locked to theremainder of the integrated blower/humidifier unit 6. The function ofthe locking handle 22 will be more fully described below in the‘humidifier unit’ section.

FIG. 3 shows the integrated blower/humidifier unit 6 with the lockinghandle 22 removed and the humidification unit 31 not shown. That is,just the blower unit 7 is shown. The top surface of the blower unit 7includes a circular humidifier aperture 1000, leading to an internalhumidifier compartment 11. The opening includes a rim 24 located aroundthe circumference of the opening. In use, a humidifier chamber 12 islocated within the internal humidifier compartment 11. The humidifierchamber 12 will be described in detail below. The humidifier chamber 12is in use fully enclosed inside the internal humidifier compartment 11,except for the uppermost part.

The internal structure of the blower unit 7 will now be described withreference to FIGS. 3 to 6. A heater base assembly 23 is located at thebottom of the internal humidifier compartment 11. The heater baseassembly 23 is mounted to the floor of the internal humidifiercompartment 11 in such a way that it has a small amount of elastic orcompression resilience. That is, it can be pushed downwards a shortdistance within the compartment, but will push back against anydownwards force that is applied. In the absence of any downwards forceit will return to its initial position.

A blower inlet port 13 and blower outlet port 14 are located on the wallof the internal humidifier compartment 11, towards the top of theinternal humidifier compartment 11. In the preferred embodiment, theseblower inlet and outlet ports 13, 14 are aligned so as to mate withhumidifier inlet and outlet ports 15, 16 located on the humidifierchamber 12 in use (described in detail below) so as to form ablower-to-humidifier gases route which allows gases to exit the blowerunit 7 and enter the humidifier chamber 12. It should be noted thatother forms of blower inlet are possible. For example a conduit runningbetween the blower unit 7 and e.g. the lid of the humidifier chamber 12.

As shown in FIG. 6, the integrated blower/humidifier unit 6 includes aninlet vent 101 to draw air in from atmosphere. The integratedblower/humidifier unit 6 also includes a mechanism for providing apressurised air flow from the inlet vent 101 to the humidifier chamber.This inlet vent 101 can be located wherever is convenient on theexternal surface of the integrated blower/humidifier unit 6. In thepreferred embodiment it is located on the rear face of the blower unit7. In the preferred embodiment, air is drawn in through the inlet vent101 by a blower fan unit 100 which acts as the preferred form ofpressured air flow mechanism. The air is ducted or otherwise directedthrough the casing to the blower inlet port 13. In use, air will exitthe main body of the blower unit 7 via the blower inlet port 13 and thenenter the humidifier chamber 12, where it is humidified and heated,before passing out of the humidifier chamber 12 through the bloweroutlet port 14, which is directly connected to the patient outlet 25.The heated humidified gas is then passed to the user 3 via e.g. aconduit 21. The patient outlet 25 is adapted to enable pneumaticattachment of the conduit 21, and in the preferred embodiment,electrical connection at the patient outlet 25 is also enabled via anelectrical connector 19. A combined electrical and pneumatic connectioncan be useful for example if the conduit 21 is to be heated. It shouldalso be noted that the outlet connection does not have to be via thehousing of the integrated blower/humidifier unit 6. If required, theconnection for the conduit 21 could be located directly on an outletfrom humidifier chamber 12.

The locking handle 22 and the integrated blower/humidifier unit 6include a locking mechanism for locking the locking handle 22 to theintegrated blower/humidifier unit 6. In the preferred embodiment thelocking mechanism is as follows: the rim 24 includes two mating grooves26 located just below the rim 24, spaced opposite each other on thecircumference of the rim 24. More than two of the mating grooves 26 canbe used if required. The grooves 26 correspond to an equal number ofmating lugs 27 on the locking handle 22. The mating groove or grooves 26have an entry point 28 on the rim 24, with the main part of the groove26 located slightly below the rim 24. The lugs 27 are pushed downwardsinto the entry points 28, and the handle is rotated so that the lugsenter the main part of the grooves 26 to hold the locking handle 22 inplace. Different locking mechanisms can be used if required.

Humidifier Chamber with Lid

The humidification unit 31 will now be described in more detail withparticular reference to FIGS. 5 and 7.

In the preferred embodiment, the humidification unit 31 is comprised ofthree main parts: humidifier chamber 12, lid 32 and locking handle 22(counted as part of the humidifier unit for the purpose of describingthe operation of the integrated blower/humidifier unit 6).

The preferred embodiment of the humidifier chamber 12 is an open-toppedcontainer, with a chamber heat conducting base 17. The humidifierchamber 12 is sized to fit snugly within the internal humidifiercompartment 11 on the integrated blower/humidifier unit 6. That is, thehumidifier chamber 12 is enclosed within the blower unit except for theopen top of the humidifier chamber 12. A fully open topped humidifierchamber is the preferred form of the humidifier chamber 12. However, analternative form of the humidifier chamber 12 could have a closed topsurface, and would include an opening on the humidifier chamber (notnecessarily on the top surface), sized appropriately so that a user caneasily fill the humidifier chamber 12.

The humidifier chamber 12 is generally circular, but the lower part ofthe rear (relative to the integrated blower/humidifier unit 6) isflattened as shown in FIGS. 7a and 7b to correspond to a ledge 33 on thelower rear side of the internal humidifier compartment 11. This ensuresthat the humidifier chamber 12 will always be oriented correctly in use.It should be understood that other methods of achieving the same resultcould also be used. For example, the humidifier chamber 12 andintegrated blower/humidifier unit 6 could include complimentary groovesand slots. The humidifier chamber 12 can also include features such as afill or level line if required. The humidifier inlet port 15 and ahumidifier outlet port 16 are located in the wall of the humidifierchamber 12, towards the top of the chamber wall. These are positioned soas to align with the blower inlet and outlet ports 13 and 14 when thehumidifier chamber 12 is in position, forming the blower-to-humidifiergases route as described above. It is preferred that the correspondingports on the blower unit 7 and humidifier chamber 12 are shaped so as tominimise air gaps. A good seal is preferred but not required. In thepreferred form, the rim or perimeter of the humidifier chamber 12includes a chamber seal 10, formed from soft silicone or similar. Whenthe humidifier chamber 12 is placed in position in the internalhumidifier compartment 11, the chamber seal 10 is pressed against thewall or walls of the internal humidifier compartment 11, and the body ofthe humidifier chamber 12 and the chamber seal 10 ensure that thehumidifier chamber 12 is sealed, so that air exiting the blower throughthe blower inlet port 13 cannot escape to atmosphere. This helps ensurethat a pressurised airstream enters the humidifier chamber 12 in use. Ifrequired, a substantially unbroken ring of sealing material such as softsilicone can be added to the wall of the internal humidifier compartment11 at or close to the upper rim of the humidifier chamber 12, to form acompartment seal (not shown) instead of or as well as the chamber seal10. In alternative embodiments the blower inlet and outlet ports 13, 14are surrounded by resilient sealing gaskets such as silicone gaskets toassist in forming a seal in use. If preferred, the resilient sealinggaskets around the ports can be used as well as the compartment and/orchamber seals.

In use, the humidifier chamber 12 is positioned (in the correctorientation) within the internal humidifier compartment 11. The lid 32is then placed on top of the humidifier chamber 12. The lid 32 is sizedso that it will pass through the top opening of the integratedblower/humidifier unit 6, with the lower surface of the lid 32 sealingonto the upper edge of the humidifier chamber 12. In the preferredembodiment, the lid 32 has an edge perimeter portion that is alignedfacing downwards. This has a circumferential recess 34 that is filledwith a silicone seal or similar which is pressed onto the upwards facingedge of the humidifier chamber 12 when the lid 32 is in position. Thisarrangement is shown in FIG. 7. In FIG. 7 the locking handle 22 is alsoshown vertically above the lid 32 (separate from the lid 32). The lid 32is sized to fit into a recess shown in the locking handle 22 (if thehandle shown in FIG. 7 is pressed vertically downwards onto the lid 32).The lid 32 is placed in position on the humidifier chamber 12 once thehumidifier chamber 12 has been filled. The locking handle 22 is thenpositioned above the lid 32. As has been described above, lugs 27 on thecircumference of the locking handle 22 engage with complimentary groovesof grooves 26 on the rim 24.

The compartment and chamber with lid are sized so that the chamber heatconducting base 17 is in contact with at least the plate 44 of theheater base assembly 23 as an upper surface of the lugs 27 contact anupper side of corresponding grooves of grooves 26. The upper side ofgrooves 26 is ramped downwards, from the entry point 28 towards theclosed end 26 a of the grooves. Rotation of the locking handle to slidelugs 27 into grooves 26 creates downwards movement of the humidifierchamber 12 against the heater base assembly 23. Once the lugs havereached the closed end 26 a of grooves 26, the humidifier chamber 12 isin a fully installed position. In the fully installed position, thechamber heat conducting base 17 is pressed against at least the plate 44of heater base assembly 23.

In normal use, a user typically presses or pushes the locking handledownwards, pushing both the lid 32 and the humidifier chamber 12downwards onto the plate 44 of the heater base assembly 23. The heaterbase assembly 23 will give slightly under the downwards pressure,allowing the locking handle 22 to be rotated so that the lugs 27 engagewith the grooves 26. Once the downwards force is removed, the humidifierchamber 12, lid 32, and locking handle 22 will be pressed upwards by thereaction force from the resiliently mounted heater base assembly 23,with the assembly held in place by the lugs 27 and grooves 26.

In the one embodiment shown in FIG. 3, the grooves 26 are shaped so thatthe locking handle 22 cannot be rotated to disengage the lugs 27 withoutpressing the locking handle 22 downwards slightly first.

In the preferred form, the top portion of the lid 32 fits into a centralrecess in the handle 22, as can best be seen in FIG. 7. The lid 32 andthe locking handle 22 are sized so that the lid 32 will snap-fit and beheld in place in the locking handle 22 to form an integrated lid unit.The lid 32 can be disengaged from the locking handle 22 by pressing onits top surface or similar. However, it is preferred that the snap-fitwill keep them engaged in normal usage. As the handle recess and the lid32 are circular, they can easily rotate relative to one another whenengaged. When the locking handle 22 is rotated to disengage it from theintegrated blower/humidifier unit 6, it will rotate easily relative tothe lid 32 (which will not rotate easily due to the seal on theperimeter edge). When the locking handle 22 has been disengaged from theintegrated blower/humidifier unit 6, it can be lifted away from theintegrated blower/humidifier unit 6 to remove both the locking handle 22and the lid 32.

Heater Base Assembly

The heater base assembly 23 has been described above as part of acombined blower/humidifier unit for the purpose of describing theoperation of the integrated blower/humidifier unit 6. However, theheater base assembly 23 forms part of a humidifier sub-unit, with theplate 44 of the heater base assembly 23 in use providing heat to thehumidifier chamber 12 for heating the liquid and gaseous contents of thehumidifier chamber 12 in order to produce water vapour for humidifyingthe gases flow through the humidifier chamber 12. The heater baseassembly 23 described below may be incorporated into an integratedblower and humidifier unit such as the integrated blower/humidifier unit6 described above, or the heater base assembly 23 may be incorporatedinto a separate humidifier unit that is used as one of severalcomponents in a modular respiratory system. Where a humidifier unit isreferred to below and in the claims, it is intended for this to meaneither a separate humidifier unit (modular system) or a humidifier unitthat is a sub-unit forming part of an integrated unit such as integratedblower/humidifier unit 6.

A heater base assembly of a typical humidifier such as those known inthe art generally has a small amount of elastic or compressionresilience, to in use provide a positive force against the base of ahumidifier chamber. A positive force between the chamber base and theheater base ensures good thermal contact between the two. A crosssection of a typical prior art heater base assembly is shown in FIG. 8.Heater plate 144 is formed from a conductive material such as aluminium,and has an upper surface which is generally planar and which acts as aheating surface in use. A heater element is attached (not shown) toprovide heat to the heating surface. In use, the conductive base of ahumidifier chamber contacts heater plate 144, the chamber base heated bythe contact with the upper heating surface of the heater plate 144, thechamber base providing heat to the contents of the chamber. In the priorart arrangement shown, the heater plate 144 is supported by a pluralityof posts 140. Posts 140 are moveably coupled to a base or base assembly156. A resilient element or elements, in this example a plurality ofhelical springs 149 corresponding with support posts 140, are providedbetween the heater plate 144 and the base 156, to bias the plate towardsthe chamber (not shown) which in use is supported by the heater plate144. In use, the chamber is pressed down onto the heater base assemblyagainst the heater plate 144, and the force of the springs 149, and islocked in place by a locking mechanism. The springs provide a positiveupwards force to bias the plate against the base of the chamber toensure good thermal contact.

The prior art assembly of FIG. 8 does not provide any fluid barrierbetween the heater plate 144 and other heater base components. Forexample, should a user spill water from a chamber onto the heater base123, water may flood beneath the heater plate 144. Such a spill can beinconvenient and difficult to clean and may cause damage to humidifieror integrated blower electrical components.

A cross section of an integrated unit that includes an embodiment of thepresent invention is shown in FIG. 10a . The integrated unit of FIG. 10includes a heater base assembly 23. The heater base assembly 23 is shownseparately and in greater detail in cross section in FIGS. 9a and 9b .With reference to FIG. 9a , the heater base assembly 23 comprises twomain parts: a heater plate 44, and a resilient member 40 which isattached to the heater plate 44.

The heater base assembly 23 will now be described in more detail withreference to FIGS. 9a and 9b . The heater plate 44 is a generally thinflat planar item in the preferred embodiment. In the preferredembodiment, at least a portion of the heater plate is formed from aheat-conductive metal such as aluminium. The heater plate 44 has athermally conductive portion 44 a, and a perimeter portion 44 b whichruns around the outside of the thermally conductive portion. Preferablythe thermally conductive portion 44 a and the perimeter portion 44 b areintegrally formed. It is preferred that at least part of and preferablythe majority of the perimeter portion 44 b is formed out of plane withthe thermally conductive portion 44 a. That is, in use, the perimeterportion 44 b is below the thermally conductive portion 44 a. Preferablyplate 44 is formed to the desired size and shape by stamping andpressing from sheet material. Alternatively heater plate 44 could bemachined from a parent material. Preferably plate 44 is round. It shouldalso be noted that although a flat planar plate has been described asthe preferred embodiment above, the plate 44 could be otherwiseshaped—for example concave or convex if required.

In the preferred embodiment, the resilient member 40 is attached toplate 44 by an over moulding process. In the preferred embodiment, atleast the perimeter portion 44 b of plate 44 is located within a mouldcavity into which an uncured or unset resilient material is injected.Following cure or setting of this material, the resilient member 40 isformed. An inner portion 40 a of the resilient member is attached to theperimeter portion 44 b of plate 44.

Preferably the resilient material is silicon or other suitable resilientor rubber material known in the art.

Preferably the perimeter portion 44 b of the plate 44 is moulded intothe resilient member following the overmoulding operation describedabove. As outlined above, it is most preferred that the perimeterportion 44 b is formed out of plane with the main portion or thermallyconductive portion of plate 44. For example, the perimeter portion 44 bof the plate 44 may be bent downwards during a cutting or stampingoperation when forming the plate 44 from a sheet material. This providesimproved mechanical strength in a direction normal to the plane of theplate 44 (this direction also being a direction in which the plate isdeflected in use), and provides improved mechanical bond strength for agiven size of heater base assembly 23. Preferably the out of planeportion of plate 44 is formed so that in use it is below that portion ofthe plate 44 which in use acts as the thermally conductive portion whichis in contact with the base of the humidifier chamber. It should benoted that ‘below’ in this context is used to indicate that theout-of-plane portion is lower than the thermally conductiveportion—‘below’ is not used in the sense that the out-of-plane portionhas to be underneath the thermally conductive portion (i.e. ‘below’ isused in the sense that the out-of-plane portion is not necessarilyobscured from view by the thermally conductive portion if the heaterplate is viewed from directly above. However, ‘below’ is used in thesense that this construction (obscured from view) is not excluded,either).

Alternatively, the perimeter portion of the plate could be formedupwardly. However this is less preferred as the resilient member, beingattached to the perimeter of the plate, would extend upwardly of theupper surface of the thermally conductive portion 44 a of the plate 44.With the perimeter portion 44 b formed downwardly according to thepreferred embodiment, the resilient member can be attached to the plateso that an upper surface of the plate 44 is adjacent to or in plane withan upper surface of the resilient member 40.

In the preferred embodiment, a heating element (indicated as item 46 inFIG. 9a ) is attached to the bottom of the plate 44. Preferably theheating element 46 is attached to the bottom of plate 44 via doublesided adhesive tape. Other electrical components such as a thermalprotection device may also be attached to the bottom of plate 44.Electrical wires associated with the heating element 46 and any otherelectrical components are routed away from the heater plate andassociated components via a channel 47 (or channels) which are formed inthe lower surface 500 of the resilient member 40, these channels runningfrom the innermost part or surface of the resilient member 40 to theoutermost part or surface of the resilient member 40. In the preferredform, the heater plate 44 is circular or substantially circular, and thechannel or channels such as channel 47 are preferably radially alignedwith respect to the plate 44.

The electrical components including the heating element 46 may beencapsulated, for example by a potting resin. A frame 48, for example aplastic frame for surrounding electrical components, may also be fixedto the bottom of the heater plate 44. If used, frame 48 provides acavity into which a potting resin may be poured. Some electricalcomponents, such as a thermal overload protection device, may be encasedby a resilient boot 59, the resilient boot being assembled onto theplate prior to encapsulating other electrical components and wires with,for example, a potting resin.

Alternatively, one or more electrical components may be encapsulated bythe resilient material which forms resilient member 40. This resilientmaterial attached to the perimeter of the plate 44 may be continuouslyformed so that it passes at least partly under the plate 44 toencapsulate one or more electrical components.

FIGS. 10a and 10b show how the heater base assembly 23 of FIG. 9a may beincorporated into a humidifier assembly. In the embodiment shown, thehumidifier assembly is part of an integrated blower/humidifier unit 6.However, the humidifier assembly could be part of a stand-alonehumidifier. The resilient member 40 has an outer part which extendsoutwards from the perimeter or perimeter portion of the heater plate 44around the perimeter or perimeter portion of the heater plate 44. Asdescribed above and as shown in FIG. 9b , the inner portion 40 a of theresilient member is attached to the perimeter portion 44 b of the heaterplate 44. The outer part provides a resilient perimeter flange 40 baround at least a part and preferably the whole of the perimeter portionof the plate. The resilient perimeter flange 40 b is clamped in asandwiched arrangement between two humidifier components. It ispreferred that the resilient perimeter flange is clamped between anupper humidifier component and a lower humidifier component.

The open-topped internal humidifier compartment 11 is defined by avertical compartment wall 54 extending substantially vertically from thebase of the compartment. In the preferred embodiment as shown, thevertical compartment wall 54 is curved around on itself so that theinternal humidifier compartment 11 is generally circular in plan view.In the preferred form shown, the flat portion 510 and ledge 33 interruptthe otherwise uniform circular nature of the internal humidifiercompartment 11. These items (flat portion 510 and ledge 33) ensurecorrect orientation of the humidifier chamber 12 within the internalhumidifier compartment 11 in use—the humidifier chamber 12 can only bepositioned in the internal humidifier compartment 11 in one orientation.A lower portion of the vertical compartment wall is preferably formed asan approximately annular horizontal section 55. Horizontal section 55forms part of the compartment base.

A humidifier compartment inner base 56 is located below the humidifiercompartment base. In the preferred form, the resilient perimeter flange40 b of the resilient member 40 is clamped between the verticalcompartment wall 54 and the compartment inner base 56. Preferably theresilient perimeter flange is clamped between the horizontal section 55and the compartment inner base 56.

The horizontal section 55 and vertical compartment wall 54 may beintegrally formed, or may be separate parts that are assembled together.Once assembled, the heater base assembly 23 and the horizontal section55 form the base of the humidifier compartment.

Alternatively, the compartment wall may not include a lower horizontalsection. In this alternative embodiment, a lower perimeter edge of thevertical wall interfaces directly with the heater base assembly 23. Inthis embodiment, the resilient perimeter flange is clamped between aperimeter edge of the vertical compartment wall 54 and the compartmentinner base, with the heater base assembly 23 forming the base of theinternal humidifier compartment 11.

The compartment inner base may form a wall of a sub housing. Forexample, as shown in FIG. 10a , the compartment inner base 56 is a topwall of a fan sub housing 400. The fan sub housing houses the blower fanunit 100.

The compartment inner base 56 may not extend across the full surface ofthe compartment base. For example, the compartment inner base 56 may beformed as an annular flange. For example, an annular flange may beattached to the compartment wall section with fasteners extendingthrough holes passing through the resilient member 40, the resilientmember 40 being clamped between the annular flange and the horizontalsection 55.

The vertical compartment wall 54 and the horizontal section 55 arefixedly coupled or attached to the compartment inner base by anysuitable attachment method known in the art. For example, the verticalcompartment wall 54 and horizontal section 55 may be attached to thecompartment inner base by screw fasteners. Alternatively the compartmentwall may be clipped to the compartment inner base, the verticalcompartment wall 54 p.m. a the horizontal section 55 and the compartmentinner base 56 sharing mating halves of a clipping arrangement.Alternatively, the vertical compartment wall 54 and the horizontalsection 55 may be attached to the outer shell 36 or other component, thecompartment inner base also being attached to the outer shell 36 or sameother component, fixedly coupling the vertical compartment wall 54 thehorizontal section 55 and the compartment inner base 56 together.

The compartment wall and the compartment inner base 56 are formed andthen assembled within the humidifier unit so that there is a fixedvertical distance between, for example, horizontal section 55 andcompartment inner base 56. The wall and base items are in the preferredembodiment formed from a rigid plastic or similar so when the humidifierunit is assembled there will always be a known, fixed distance betweenthese items or e.g. the edges and walls thereof. The fixed verticaldistance between the vertical compartment wall 54 the horizontal section55 and the compartment inner base 56, at least a portion of theresilient perimeter flange 40 b is compressed slightly. Compression ofthe resilient member 40 assists with maintaining the position of theheater base assembly 23 within the humidifier unit assembly.

The resilient member provides a water or fluid barrier between theoutside or user accessible surfaces of the humidifier and internalcomponents of the humidifier. Compression of the resilient perimeterflange 40 b between the vertical compartment wall 54 the horizontalsection 55 and the compartment inner base 56 creates a fluid or waterbarrier between the heater base assembly 23 and the vertical compartmentwall 54 and the horizontal section 55. A compressed portion of theresilient perimeter flange 40 b provides a fluid barrier between theheater base assembly 23 and the upper humidifier component. Thecompressed portion of the resilient perimeter flange 40 b provides afluid barrier between the heater base assembly 23 and the humidifiercompartment wall. In the assembled humidifier unit, the heater baseassembly 23 forms at least a part of the base of the internal humidifiercompartment 11. A fluid or water barrier between the heater baseassembly 23 and the compartment wall ensures that at least some liquidspilt inside the humidifier compartment cannot reach the internalcomponents of the humidifier unit. Liquid spills are preferablycontained within the internal humidifier compartment 11.

Preferably the water barrier provided by the resilient member 40 is aseal that provides a water tight barrier between the heater baseassembly and the mating humidifier components such as the humidifiercompartment wall. Alternatively, the water barrier may provide a partialseal between the heater base assembly and the humidifier; even apartially water tight barrier that prevents some spilt fluid frompassing from the humidifier compartment to the internal components ofthe humidifier unit can provide a useful benefit.

Preferably an upward surface 400 a of the resilient perimeter flange isoff set downwardly relative to the upper surface 400 b of the innerportion 40 a of the resilient member attached to the plate 44, so that,when assembled together, an upper surface of the compartment wallhorizontal section is approximately in plane with the upper surface 400b of the resilient member 40 attached to plate 44.

As shown in FIGS. 9a and 9b , the fluid barrier portion 45 in thepreferred embodiment of resilient member 40 is formed as follows: anupper groove 43 is formed in an upper surface of the resilient member.The compartment wall horizontal section has a corresponding upperprojection 53 extending downwards, which locates into the upper groove43 when the humidifier unit is assembled. Preferably the upper groove 43extends continuously around the resilient member, the upper groove 43being located intermediate between an outer perimeter 40 c of theresilient member and an outer perimeter of the plate 44. Preferably theupper projection 53 extends continuously around an inner perimeterportion of the horizontal section 55, as shown in FIGS. 10a and 10b .Alternatively, the upper projection 53 may extend continuously aroundthe compartment wall horizontal section at a position intermediatebetween an inside perimeter of the horizontal section 55 and thevertical compartment wall 54.

Preferably the upper projection 53 is tapered to assist with alignmentof the compartment wall with the heater base assembly 23 during assemblyof the humidifier unit. Preferably the upper groove 43 iscorrespondingly tapered, tapering from a wide mouth to a narrow base.

The upper projection 53 provides a reduced cross sectional area foreasier compression of the resilient member 40, when compared to noprojection. This allows for easier assembly of the humidifier unit as areduced force is required to compress the resilient member to a desiredstate of compression. Compression of the resilient member 40 between theupper projection 53 and the compartment inner base creates the fluidbarrier for containing fluid spills within the internal humidifiercompartment 11.

In the most preferred form, the fluid barrier portion 45 in theresilient member 40 is further formed by the inclusion of a secondgroove 42 formed in the lower surface 500 of the resilient member 40. Inthe preferred form, the compartment inner base also has a correspondinglower projection 52 which in use extends upwards and locates within thesecond groove 42 when the humidifier unit is assembled. Preferably thesecond groove 42 extends continuously around the resilient perimeterflange 40 b, the second groove 42 being located intermediate between theouter perimeter 40 c of the resilient member and the outer perimeter ofthe plate 44. In the preferred embodiment, the lower projection 52extends continuously around the compartment inner base 56 andcorresponds to the continuous second groove 42.

In the preferred embodiment, the lower projection 52 is tapered toassist with alignment of the heater base assembly 23 onto thecompartment inner base during assembly of the humidifier unit. In themost preferred form, the second groove 42 is tapered from a wide mouthto a narrow base.

The lower projection 52 provides a reduced cross sectional area foreasier compression of the resilient member 40. This allows for easierassembly of the humidifier unit as a reduced force is required tocompress the resilient member to a desired compression. Compression ofthe resilient member between the lower projection 52 and the compartmenthorizontal section assists in forming a fluid barrier which containsfluid spills within the internal humidifier compartment 11.

As outlined above, in the preferred form, the heater base assembly 23has the upper groove 43 and second groove 42. Preferably the second andupper grooves 42, 43 are aligned in a vertical direction—that is, whenassembled into the humidifier unit and in use, the upper groove 43 isdirectly above the second groove 42. The part of the resilient member 40that is sandwiched between the vertically aligned lower and upperprojections 52, 53 acts as the fluid barrier for containing spillswithin the internal humidifier compartment 11. Preferably the dimensionsof the projections, the set distance between the projections, and thecorresponding thickness of resilient material located between the secondand upper grooves 42, 43 are calculated so that a vertical compressionof the resilient member of approximately 12% is achieved when thehumidifier unit is assembled. However, any range of compression between4% and 20% has been found to be acceptable. A wider range could also beconsidered, although this is not preferred.

The resilient material either side of the fluid barrier portion 45 maybe slightly compressed. Alternatively, the resilient material eitherside of the fluid barrier portion 45 can remain uncompressed in theassembled humidifier unit. It is most preferred that the resilientmaterial outside of the fluid barrier portion 45 (e.g. the materialbetween the outer perimeter 40 c and the seal portion 45) is compressedslightly in the assembled humidifier unit. This compression of theresilient material outside of the fluid barrier portion 45 is less thanthe compression of the fluid barrier portion 45. Alternatively, theresilient material outside of the fluid barrier portion 45 can remainuncompressed in the assembled humidifier unit.

The material within the fluid barrier portion 45 (e.g. the materialbetween the fluid barrier portion 45 and the plate 44) is compressedslightly in the assembled humidifier unit. This compression of theresilient material within the fluid barrier portion 45 is less than thecompression of the fluid barrier portion 45. Alternatively, theresilient material within the fluid barrier portion 45 can remainuncompressed in the assembled humidifier unit.

As can be seen from the above description, the fluid barrier portion ofthe resilient member is clamped between or sandwiched between thevertically aligned lower and upper projections 52, 53. The inner portion40 a of the resilient member 40 is overmoulded and permanently connectedto the heater plate 44. Therefore, the resilient member 40 provides afluid barrier between the heater base assembly 23 and the humidifiercompartment wall. Additionally the resilient member 40 acts as asuspension member as will now be described.

As shown in FIGS. 10a and 10b , in the preferred embodiment, a gap 50 isprovided between the heater base assembly 23 and the compartment innerbase. The gap 50 is between the lower surface 500 of the resilientmember 40 and an upper surface of the compartment inner base 56. In use,the heater plate and a portion of the resilient member are displaceddownwardly (with the clamped portion or resilient perimeter flange ofthe resilient member 40 remaining in place). Alternatively, thecompartment inner base 56 may be absent except for the portion of thecompartment inner base 56 clamping the resilient perimeter flange 40 b.

The gap 50 allows vertical downward movement of that part of the heaterbase assembly 23 which is not clamped. The gap 50 is present when theresilient member 40 is un-deflected. The resilient member 40 isun-deflected when the humidifier chamber 12 is not installed within theinternal humidifier compartment 11 with the plate 44 in a raised oruninstalled position. As described previously, to install the humidifierchamber 12 within the internal humidifier compartment 11, the humidifierchamber 12 is positioned within the internal humidifier compartment 11and the lid 32 is then placed on top of humidifier chamber 12. The lid32 and locking handle 22 is pressed down slightly, allowing the lockinghandle to rotate so that the lugs 27 engage with grooves 26. Pressingthe lid and locking handle downwards presses the chamber heat conductingbase 17 of humidifier chamber 12 onto the heater base assembly 23. Theresilient member 40 of heater base assembly 23 and the gap 50 beneaththe heater base assembly 23 allows the heater plate 44 to move downwardswith respect to the vertical compartment wall 54 and the horizontalsection 55. With the humidifier chamber 12 in the installed position,the resilient member 40 remains in a deflected state. In the deflectedstate, the resilient member 40 provides an upwards force, pressing orbiasing the thermally conductive portion 44 a of heater plate 44 againstthe base of e.g. humidifier chamber 12 to ensure good thermal contact.

It should be noted that the way in which the humidifier chamber 12 locksto or is held by the humidifier unit in an installed position is notimportant. For example, a humidifier assembly according to the presentinvention may not enclose the humidifier chamber within a chambercompartment as in the preferred embodiment described above. Otherretaining or locking mechanisms other than the grooves 26 and lugs 27described above may be used to retain the chamber in an installedposition where the heater plate is displaced downwardly against theaction of the deflected resilient member 40.

As shown in FIG. 7a or FIG. 7b , the chamber heat conducting base 17preferably extends slightly proud of the periphery portion 18 of thebase. As best shown in FIG. 9a , in the preferred embodiment, theresilient member 40 does not extend all the way across the top surfaceof the heater plate 44, but forms a circumferential ridge above andaround the outside perimeter of the heater plate 44. The chamber heatconducting base 17 and the resilient member 40 are dimensioned so thatthe chamber heat conducting base 17 will fit within the saucer sectionformed by the ridge of resilient member 40 attached to the heater plate44, and the chamber heat conducting base 17 directly contacts the heaterplate 44 over substantially the whole of the surface of the chamber heatconducting base 17. In the preferred embodiment, the amount which thechamber heat conducting base 17 extends downwardly proud of theperiphery portion 18 is slightly greater than the thickness or height ofthe ridge of resilient material above the surface of the heater plate44, to ensure there is no interference between the resilient member 40and the humidifier chamber, so that good contact between plate 44 andchamber heat conducting base 17 occurs. Alternatively the whole base ofthe humidifier chamber may fit within the inner dimension of theresilient member.

Preferably the gap 50 allows enough vertical movement of the heaterplate 44 to allow the locking handle lugs 27 to lock fully into grooves26 without the gap 50 completely closing. This ensures the humidifierchamber may be installed by downwards deflection of the resilient memberonly—that is, without further significant compression of the resilientmember. This helps ensure that the force required to press the chamberinto position does not become excessive. For example, in the preferredembodiment, the gap provides approximately 1.1 mm of vertical travel,and the amount of vertical travel required to slide locking lugs 27 fromthe entry point 28 into grooves 26 is approximately 0.7 mm.

When deflected downwards, the resilient member 40 provides an upwardsforce to the heater plate so that the heater plate 44 is pressed againstthe chamber heat conducting base 17.

The inventors have found that a force of approximately 29N is desirablefor pressing the chamber onto heater plate 44 (and vice versa) to fullyinstall the humidifier chamber 12 within the internal humidifiercompartment 11. A force of this magnitude is not overly difficult for auser to over come by rotation of the locking handle lugs 27 into grooves26, and this amount of force provides good contact pressure between thechamber heat conducting base 17 and the heater plate 44 for good thermalconnection.

To achieve a desirable deflection force required to install thehumidifier chamber 12 into the internal humidifier compartment 11, theresilient member further has a necked or narrow section 49 locatedbetween the inner portion 40 a and the clamped portion of the resilientmember 40. Narrow section 49 is formed by forming or including a valley41 in either the lower or the upper side or surface of the resilientmember 40. It is preferred that the valley 41 is formed in the bottomsurface of the resilient member as shown in FIGS. 9a and 9b .Alternatively, the valley may be formed in the upper surface of theresilient member 40, or both surfaces of the resilient member.

Movement of the heater plate 44 downwards from a resting position isachieved by deflection of the resilient member 40. The clamped portionof the resilient perimeter flange 40 b is clamped in position andremains stationary relative to the humidifier assembly as outlinedabove. The inner part or inner portion 40 a is attached to the heaterplate 44 and moves downwards with the heater plate 44 when thehumidifier chamber is placed in position. Elastic deflection of theresilient member 40 between the inner portion 40 a and the clampedportion generally occurs through the narrow section 49. The resilientmember 40 deforms (generally through the narrow section 49) as it isdeflected during downwards movement of the heater plate 44, and an innerside 51 of the upper groove 43 may deflect away from the upperprojection 53, creating a crevice between the inner side 51 and a sideof the upper projection 53. Liquid from a spill inside the compartmentmay enter the crevice. However, once the humidifier chamber 12 isremoved from the internal humidifier compartment 11, the resilientmember deflects back to a resting shape, closing the inner side 51 ofthe upper groove 43 against the corresponding side of the upperprojection 53. This closing of the crevice squeezes liquid from the areabetween the upper groove 43 and upper projection 53. Due to thecompression of the fluid barrier portion 45, no liquid passes beyond thefluid barrier provided by the resilient member, even with maximumdeflection of resilient member 40.

In an alternative embodiment, the resilient member is formedcontinuously across the upper surface of the heater plate, completelycovering the upper surface of the heater plate. During the over mouldingprocess, the uncured or unset resilient material is allowed to flashacross the upper surface of the heater plate 44, creating a heater baseassembly with a continuous resilient material upper surface. Theresilient material covering electrically isolates the heater plate fromuser contact, and provides corrosion protection.

In a further alternative embodiment, the heater element may be attachedto the compartment inner base or other humidifier component. In thisalternative embodiment, the heater element does not contact the heaterplate 44 when the heater plate 44 is in a raised position with theresilient member 40 in an un-deflected state. When the humidifierchamber is installed within the humidifier compartment, the heater plate44 is moved downwards against the action of the deflected resilientmember 40 to a lowered position. In the lowered position, the bottom ofthe heater plate 44 makes thermal contact with the heating elementattached to the inner compartment base or other humidifier component toheat the heater plate and the conductive base of the chamber above. Thisembodiment has the advantage that the heater plate 44 cools more quicklywhen the chamber is removed from the internal humidifier compartment 11,as contact between the heater plate 44 and the heater element is lostwhen the humidifier chamber 12 is removed from the heater plate 44. Theheater element is preferably elastically mounted to the innercompartment base or other humidifier component to allow some verticalmovement of the element once in contact with an underside of the heaterplate. The spring constant of the elastic mounting of the heatingelement may be different to the spring constant of the elastic mountingof the heater plate. For example, the spring constant of the elasticmounting of the heating element could be higher than the spring constantof the elastic mounting of the heater plate.

An alternative heater base assembly is illustrated in FIG. 11. The sameitem numbering used to describe the previous embodiment of FIGS. 9a and9b have been used to describe like parts of the alternative embodimentof FIG. 11.

A difference between the embodiments of FIGS. 9 and 11 is the crosssectional shape of the resilient member 40. The resilient member in theheater base assembly 23 of FIG. 11 is preferably attached to the plate44 and assembled to a humidifier assembly as previously described withreference to the embodiment of FIGS. 9a and 9b . With reference to FIG.11, an inner portion 40 a of the resilient member 40 is attached to aperimeter portion 44 b of plate 44. Preferably the resilient member ismoulded to the plate. As shown in FIG. 11, the resilient member ismoulded or attached to a lower surface of the plate. An outer part ofthe resilient member forms a resilient perimeter flange 40 b around atleast a part and preferably the whole of the perimeter portion of theplate. The resilient perimeter flange 40 b is claimed in a sandwichedarrangement between two humidifier components, the horizontal section 55and compartment inner base 56 in FIG. 11. A fluid barrier is formedbetween the heater base assembly and a humidifier compartment aspreviously described with reference to the embodiment of FIG. 9.

Bridging between the inner portion 40 a and the resilient perimeterflange 40 b of the resilient member is a skirt portion 40 d. The skirtportion 40 d allows vertical movement of the heater plate 44 withrespect to the resilient perimeter flange of the resilient member.

In the illustrated embodiment, the skirt portion 40 d spaces the innerportion 40 a of the resilient member from the resilient perimeter flange40 b of the resilient member. A vertical gap 50′ between the inner andouter parts of the resilient member allow vertical movement of theheater plate 44 relative to the outer part of the resilient member fixedto the humidifier assembly. The gap 50′ is present when the resilientmember is un-deflected, when the humidifier chamber 12 is not installedwithin the humidifier compartment with the plate 44 in a neutral ornon-displaced position. Once the chamber is installed into thehumidifier and on the heater base, the resilient member is deflected. Inthe deflected state, the resilient member provides an upwards force tobias the plate 44 against the base of humidifier chamber 12.

Preferably the gap 50′ provides enough vertical movement to allow achamber to be installed onto the heater base without the gap 50′ fullyclosing, as previously described with reference to the embodiment ofFIG. 9.

The amount of force required to displace the heater plate downwards maybe determined by the thickness of the skirt portion 40 d of theresilient member 40 or the length of the skirt section or both.

The resilient member provides a gasket or diaphragm between the heaterplate 44 and the humidifier structure to resiliently mount the heaterplate 44 within the humidifier assembly. The intermediate portion of theresilient member bridging between the clamped portion of the resilientmember and the inner portion of the resilient member coupled to theplate 44 allows vertical movement of the heater plate.

Further alternative embodiments may present themselves to a personskilled in the art without departing from the present invention. Forexample, the resilient member may form a bellows shape or other shapedesigned to achieve a desired amount of resistance to displacement ofthe heater plate relative to the humidifier base or casing.

Furthermore, the resilient member may be alternatively attached to acomponent fixed to the heater plate. For example, the resilient membermay be moulded or otherwise attached to the frame 48 attached to thebottom of the heater plate 44. Attachment of the frame to the heaterplate couples the resilient member to the heater plate without directbonding between the heater plate and the resilient member.

The heater base assembly according to the present invention is avertically compact assembly. When assembled into a casing as part of ahumidifier assembly, the compact nature of the heater base assemblyhelps to reduce the humidifier assembly or integrated unit assemblyheight to assist in achieving a desirable compact unit for home use. Theheater base assembly according to the present invention when assembledas part of a humidifier assembly or integrated unit provides a fluidbarrier that prevents or at least reduces spills contacting internalblower or humidifier components and contains spills within thehumidifier compartment. The heater base assembly according to thepresent invention has a resilient element that in use acts to provide adesirable amount of force between the heater plate 44 and the conductivebase of the humidifier chamber, to bias the heater plate against thebase of the chamber. In the context of this specification, a desirableamount of force is an amount of force which can be easily overcome by auser when installing a humidification chamber into the humidifier, yetprovides sufficient contact force to achieve good thermal contactbetween the chamber base and heater plate.

The foregoing description of the invention includes preferred formsthereof. Modifications may be made thereto without departing from thescope of the invention as claimed.

It should also be noted that when terms such as for example ‘top’,‘bottom’, ‘above’, ‘below’, ‘upper surface’, ‘lower surface’ and‘underside’ are used, these refer to the orientation of the devicedescribed or claimed when it is in use. These terms are used to describethe orientation or location of features relative to one another when thedevice is in use, and when these terms are used, should be read in thismanner. Use of these terms is not intended to limit the device asdescribed or claimed in any other fashion.

1.-19. (canceled)
 20. A heater base assembly for use in a humidifierconfigured to heat and humidify a flow of respiratory gases supplied toa user comprising: a heater plate having a thermally conductive portionand a perimeter portion around a perimeter of the heater plate; and aresilient member having a first portion coupled to the heater plate anda second portion adapted to provide a flange around at least part of theperimeter portion, the resilient member adapted to allow the heater baseassembly to be fixed to the humidifier in use by the flange in such amanner that the heater plate and the first portion is configured to moverelative to the humidifier in use.
 21. The heater base assembly of claim20, wherein the resilient member is a flexible gasket or diaphragm forresiliently fixing the heater plate to the humidifier.
 22. The heaterbase assembly of claim 20, wherein the resilient member is moulded tothe heater plate.
 23. The heater base assembly of claim 20, wherein thefirst portion is attached to the perimeter portion.
 24. The heater baseassembly of claim 20, wherein the flange extends around a full perimeterof the heater plate.
 25. The heater base assembly of claim 20, whereinthe resilient member is adapted to allow the heater base assembly to befixed to the humidifier by the flange in such a manner that the heaterplate and the first portion are configured to move relative to thehumidifier in a direction substantially transverse to a general plane ofthe heater plate.
 26. The heater base assembly of claim 20, wherein thethermally conductive portion of the heater plate is substantiallyplanar, and at least part of the perimeter portion is formed out ofplane from the thermally conductive portion.
 27. The heater baseassembly of claim 20, wherein a portion of the flange is adapted to inuse provide a fluid barrier between the heater base assembly and ahumidifier component.
 28. The heater base assembly of claim 20, whereinthe resilient member comprises a narrow section formed in the resilientmember between the first portion and the flange.
 29. The heater baseassembly of claim 28, wherein the narrow section provides an area inwhich the resilient member is configured to elastically deflect when theheater plate is displaced relative to the flange of the resilient memberin a direction substantially transverse to a general plane of the heaterplate in use.
 30. The heater base assembly of claim 28, wherein thenarrow section comprises a circumferential valley formed in either anupper surface or a lower surface of the resilient member or both. 31.The heater base assembly of claim 20, wherein the resilient membercomprises a skirt section formed in the resilient member between thefirst portion and the flange, in use the skirt section elasticallydeflecting when the heater plate is displaced relative to the flange ofthe resilient member in a direction substantially transverse to ageneral plane of the heater plate.
 32. The heater base assembly of claim31, wherein the first portion is vertically spaced from the flange bythe skirt section.
 33. The heater base assembly of claim 20, wherein theresilient member is formed as a continuous layer across an upper surfaceof the heater plate, the continuous layer completely covering the uppersurface.
 34. The heater base assembly of claim 20 further comprising aheating element attached to an underside of the heater plate.
 35. Theheater base assembly of claim 20, wherein in use the resilient memberforms a fluid barrier between the heater plate and the humidifier.